In the primary analysis, changes in serum CTx level, BMD, and cellular OPG/RANKL expression from baseline through week 24 will be quantitated and subsequently compared between treatment arms. In addition, the impact of zoledronic acid administration on these covariates will be assessed at various study time points. The relationship between OPG/RANKL expression, immune activation, serum bone regulating hormonal levels, and bone turnover will be evaluated.